Merge pull request #61 from precariouspanther/ISSUE-60-float-innerlog…

…10-div-zero

ISSUE-60: Fix for division by zero caused by float precision

src/Decimal.php

@@ -1203,6 +1203,7 @@ private static function innerLog10(string $value, int $in_scale, int $out_scale)
         switch ($cmp) {
             case 1:
                 $value_log10_approx = $value_len - ($in_scale > 0 ? ($in_scale+2) : 1);
+                $value_log10_approx = max(0, $value_log10_approx);
 
                 return \bcadd(
                     (string)$value_log10_approx,

tests/regression/issue60Test.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+use Litipk\BigNumbers\Decimal;
+use PHPUnit\Framework\TestCase;
+
+class issue60Test extends TestCase
+{
+    public function test_that_fromFloat_division_does_not_calculate_invalid_log10_avoiding_div_zero()
+    {
+        $value = Decimal::fromFloat(1.001);
+        $divisor = Decimal::fromFloat(20);
+
+        $this->assertEquals(0.05005, $value->div($divisor)->asFloat());
+        $this->assertEquals(0.000434077479319, $value->log10()->asFloat());
+    }
+
+    public function test_that_fromFloat_less_than_1_still_correct()
+    {
+        $value = Decimal::fromFloat(0.175);
+        $divisor = Decimal::fromFloat(20);
+
+        $this->assertEquals(0.009, $value->div($divisor)->asFloat());
+        $this->assertEquals(-0.7569, $value->log10()->asFloat());
+    }
+}